Teamcasa:
True, but it's not Charles' Law.
*dave*:
Don't feel like the Lone Ranger. I only discovered my similar error about 10 or 11 years ago. I had thought it was Gay-Lussac's Law.
Gas laws as they relate to divers...intellectual discussion
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True, but it's not Charles' Law.
Don't feel like the Lone Ranger. I only discovered my similar error about 10 or 11 years ago. I had thought it was Gay-Lussac's Law.
Timeliner
Contributor
I remember there were Gas Laws back during the Carter Administration and we'll probably have them again soon.
I don't like Gas Laws so Ya'll go on back home.
I don't like Gas Laws so Ya'll go on back home.
richerso
Contributor
Can't say I can really add anything to what has already been said.
Most of what I read here (*this thread) seems to be focused on the gas mechanics of expanding gases, etc. That is all good. Certainly teach that in class. But I would make a special point to explain Dalton's law in detail. Then, make a point of showing how Dalton's law is central in describing N2 pressure, O2 pressure, and possibly He pressure at depth as it is exposure to these pressures and times that allow us to predict (as practicably as we can) narcosis, O2 toxicity and decompression theory.
From there, you have the confidence that you have adequately provided the gas theory. Now provide the physiological effects. To the best of my knowledge (and I am a newbie here), nitrogen narcosis effects are predicted based upon empirical data only. O2 toxicity is predicted based upon empirical data only. I believe there is a nitrogen loading theory (decompression theory); but I am unfamiliar with it. Call me back in a few months after I go through trimix training.
Most of what I read here (*this thread) seems to be focused on the gas mechanics of expanding gases, etc. That is all good. Certainly teach that in class. But I would make a special point to explain Dalton's law in detail. Then, make a point of showing how Dalton's law is central in describing N2 pressure, O2 pressure, and possibly He pressure at depth as it is exposure to these pressures and times that allow us to predict (as practicably as we can) narcosis, O2 toxicity and decompression theory.
From there, you have the confidence that you have adequately provided the gas theory. Now provide the physiological effects. To the best of my knowledge (and I am a newbie here), nitrogen narcosis effects are predicted based upon empirical data only. O2 toxicity is predicted based upon empirical data only. I believe there is a nitrogen loading theory (decompression theory); but I am unfamiliar with it. Call me back in a few months after I go through trimix training.
BarryTX
Contributor
Just to add a couple of centavos - if the purpose of the class is to give instruction to folks who have never dived or taken a Scuba class, IMHO Boyles law is by far the most important to discuss. Learning about nitrogen saturation, decompression, and oxygen toxicity is important, but I expect few people with no background would guess that an overexpansion injury or death therefrom could occur by taking a breath at 15 ft depth and then surfacing without exhaling. It is an eye opener to realize how much air expands / compresses between shallow depths and surface or vice versa.
One other minor and rather picky point - Charles' law isn't completely without application to diving, since water temperature can change significantly with depth. Certainly the hydrostatic pressure of the water is by far the greatest and most important effect, but the change in temperature will also play a minor role in the volume change of air in a BC for example. In practice it is negligible compared to the effect described by Boyle's law. And yes, Charles kept it simple by dealing with no pressure change, but the bottom line is he described changes in volume of gases with changes in temperature. In the end, the work of all of these folks combined to form the ideal and real gas laws.
One other minor and rather picky point - Charles' law isn't completely without application to diving, since water temperature can change significantly with depth. Certainly the hydrostatic pressure of the water is by far the greatest and most important effect, but the change in temperature will also play a minor role in the volume change of air in a BC for example. In practice it is negligible compared to the effect described by Boyle's law. And yes, Charles kept it simple by dealing with no pressure change, but the bottom line is he described changes in volume of gases with changes in temperature. In the end, the work of all of these folks combined to form the ideal and real gas laws.
ZzzKing
Contributor
I remember there were Gas Laws back during the Carter Administration and we'll probably have them again soon.
I don't like Gas Laws so Ya'll go on back home.
Quit being a crotchety old bass turd.
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